Bicycle controller and bicycle control system including bicycle controller

ABSTRACT

A bicycle controller includes an electronic control unit that controls a transmission device. The transmission device is configured to change a ratio of a rotational speed of a wheel of a bicycle to a rotational speed of a crank of the bicycle, and a motor. The motor transmits torque to an upstream side of the transmission device in a transmission path of manual driving force that is input to the crank. The electronic control unit is configured to switch between a first mode that drives the motor in accordance with the manual driving force and a second mode that allows the motor to be driven to assist walking of the bicycle. The electronic control unit is configured to control a rotational speed of the motor in accordance with the ratio in the second mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/787,191 filed on Oct. 18, 2017. The entire disclosure ofU.S. patent application Ser. No. 15/787,191 is hereby incorporatedherein by reference. This application claims priority to Japanese PatentApplication No. 2016-213622, filed on Oct. 31, 2016. The entiredisclosure of Japanese Patent Application No. 2016-213622 is herebyincorporated herein by reference.

BACKGROUND Technical Field

The present invention generally relates to a bicycle controller and abicycle control system including a bicycle controller.

Background Information

Japanese Laid-Open Patent Publication No. 2012-144061 (Patentdocument 1) discloses a bicycle controller that drives a motor if anoperation unit is operated to assist propulsion of a bicycle when arider walks the bicycle.

SUMMARY

In Patent document 1, the bicycle controller controls the motor inaccordance with the rotational speed of the motor that is predeterminedfor a case in which the rider walks the bicycle. However, the bicyclecontroller of Patent document 1 does not take into account bicycles thatinclude transmission devices.

It is an object of the present invention to provide a bicycle controllerand a bicycle control system for a bicycle controller comprising anelectronic control unit that controls a transmission device. Thetransmission device is configured to change a ratio of a rotationalspeed of a wheel of a bicycle to a rotational speed of a crank of thebicycle, and a motor. The motor transmits torque to an upstream side ofthe transmission device in a transmission path of manual driving forcethat is input to the crank. The electronic control unit is configured toswitch between a first mode that drives the motor in accordance with themanual driving force and a second mode that allows the motor to bedriven to assist walking of the bicycle. The electronic control unit isconfigured to control a rotational speed of the motor in accordance withthe ratio in the second mode.

It is an object of the present invention to provide a bicycle controlleran electronic control unit that controls a transmission device. Thetransmission device is configured to change a ratio of a rotationalspeed of a wheel of a bicycle to a rotational speed of a crank of thebicycle, and a motor. The motor transmits torque to an upstream side ofthe transmission device in a transmission path of manual driving forcethat is input to the crank. The electronic control unit is configured toswitch between a first mode and a second mode. The first mode drives themotor in accordance with the manual driving force. The second modeallows the motor to be driven to assist movement of the bicycle while arider walks and pushes the bicycle. The electronic control unit isconfigured to control the transmission device to decrease the ratio upondetection of an output torque of the motor becoming greater than orequal to a predetermined torque while in the second mode.

The present invention provides a bicycle controller and a bicyclecontrol system for a bicycle including a transmission device that uses amotor in an optimal manner when the rider walks and pushes the bicycle.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure.

FIG. 1 is a side elevational view of a bicycle controller and a bicyclecontrol system in accordance with a first embodiment.

FIG. 2 is a schematic diagram of a manual driving force transmissionpath in a bicycle shown in FIG. 1.

FIG. 3 is a block diagram showing the electrical configuration of thebicycle control system shown in FIG. 1.

FIG. 4 is a front elevational view of an operation device of the bicyclecontrol system shown in FIG. 1.

FIG. 5 is a flowchart of a switching control executed by an electroniccontrol unit shown in FIG. 1.

FIG. 6 is a flowchart of a drive control executed by the electroniccontrol unit shown in FIG. 1.

FIG. 7 is a flowchart of a switching control executed by the electroniccontrol unit in accordance with a second embodiment.

FIG. 8 is a flowchart of a drive control executed by the electroniccontrol unit in accordance with the second embodiment.

FIG. 9 is a flowchart of a drive control executed by the electroniccontrol unit in accordance with a third embodiment.

FIG. 10 is a flowchart of a switching-drive control executed by theelectronic control unit in accordance with a fourth embodiment.

FIG. 11 is a flowchart of a switching control executed by the electroniccontrol unit in accordance with a fifth embodiment.

FIG. 12 is a flowchart of a drive control executed by the electroniccontrol unit in the fifth embodiment.

FIG. 13 is a flowchart of a drive control executed by the electroniccontrol unit in accordance with a sixth embodiment.

FIG. 14 is a flowchart of a drive control executed by the electroniccontrol unit in accordance with a seventh embodiment.

FIG. 15 is a flowchart of a switching control executed by the electroniccontrol unit in accordance with an eighth embodiment.

FIG. 16 is a flowchart of a drive control executed by the electroniccontrol unit in accordance with a ninth embodiment.

FIG. 17 is a flowchart of a switching-drive control executed by theelectronic control unit in accordance with a tenth embodiment.

FIG. 18 is a flowchart of a drive control in accordance with a firstmodification.

FIG. 19 is a schematic diagram of a manual driving force transmissionpath of a bicycle in accordance with a second modification.

DETAILED DESCRIPTION OF EMBODIMENTS

Selected embodiments will now be explained with reference to thedrawings. It will be apparent to those skilled in the bicycle field fromthis disclosure that the following descriptions of the embodiments areprovided for illustration only and not for the purpose of limiting theinvention as defined by the appended claims and their equivalents.

First Embodiment

A bicycle provided with a bicycle controller in accordance with a firstembodiment and a bicycle control system including the bicycle controllerwill now be described with reference to FIGS. 1 to 6. As shown in FIG.1, a bicycle 10 includes a front wheel 12, a rear wheel 14, a bicyclebody 16, a drive mechanism 18 and a bicycle control system 50. Thebicycle body 16 includes a frame 20, a front fork 22 connected to theframe 20, and a handlebar 24 connected in a removable manner by a stem24A to the front fork 22. The front fork 22 is supported by the frame 20and connected to an axle 12A of the front wheel 12.

A manual driving force TA is transmitted by the drive mechanism 18 tothe rear wheel 14 to move the bicycle 10. The drive mechanism 18includes a crank 26, two pedals 28, an output portion 30 (refer to FIG.2), a front rotation body 32, a rear rotation body 34 and a chain 36.

The crank 26 includes a crankshaft 38 and two crank arms 40. Thecrankshaft 38 is rotatably supported by a housing 72 of an assist deviceA that is coupled to the frame 20. The two crank arms 40 are coupled tothe crankshaft 38. The two pedals 28 each include a pedal body 28A and apedal shaft 28B. The pedal shaft 28B is coupled to the correspondingcrank arm 40. The pedal body 28A is rotatably supported by the pedalshaft 28B.

The front rotation body 32 is coupled by the output portion 30 to thecrankshaft 38. The front rotation body 32 is coaxial with the crankshaft38. The rear wheel 14 includes a hub (not shown). In one example, thefront rotation body 32 includes a front sprocket, and the rear rotationbody 34 includes a rear sprocket. The chain 36 is wound around the frontrotation body 32 and the rear rotation body 34. A manual driving forceapplied to the pedals 28 rotates the crank 26 in one direction. Thismanual driving force of the pedals 28 rotates the wheel 14 with thefront rotation body 32, the chain 36, and the rear rotation body 34 inthe same direction. In a further example, the front rotation body 32includes a front pulley, and the rear rotation body 34 includes a rearpulley that is connected by a belt to the front rotation body 32. Inanother example, the front rotation body 32 includes a front bevel gear,and the rear rotation body 34 includes a rear bevel gear that isconnected by a drive shaft to the front rotation body 32.

As shown in FIG. 2, the crank 26, the output portion 30, the frontrotation body 32, the rear rotation body 34, a transmission device 52 ofthe bicycle control system 50, and the wheel 14 form a transmission pathfor the manual driving force TA that is input to the crank 26.

As shown in FIG. 3, the bicycle control system 50 includes a bicyclecontroller 90, the transmission device 52 and a motor 54. In oneexample, the bicycle control system 50 includes a clutch 56 (refer toFIG. 2), a transmission operation unit 57, an operation device 58, abattery unit 60, a torque sensor 62, a rotational angle sensor 64 and avehicle speed sensor 66.

As shown in FIG. 3, the transmission device 52 and an actuator 70 form atransmission apparatus S. The transmission device 52 is configured tochange a ratio R of the rotational speed of the wheel 14 to a rotationalspeed N of the crank 26. The transmission device 52 is configured tochange the ratio R in steps. In one example, the transmission device 52changes the speed of the rotational input to the crankshaft 38 andtransmits the rotation to the wheel 14. The transmission device 52includes an internal transmission device. The internal transmissiondevice is arranged in a hub of an axle 14A of the wheel 14 (refer toFIG. 1). The actuator 70 is an electric motor. The transmission device52 is driven by the actuator 70 to perform speed-changing operationsthat change the ratio R in steps. The speed-changing operations includean operation for changing the connection of gears that form a planetarygear mechanism inside the transmission device 52. The internaltransmission device can include a Continuously Variable Transmission(CVT) instead of the planetary gear mechanism. In one example, the CVTmechanism is formed by a planetary mechanism that includes an inputbody, an output body and a transmission body. The transmission body isrotated to continuously vary the ratio R. The transmission operationunit 57 is operable by a rider. The transmission operation unit 57 isattached to the handlebar 24 of the bicycle 10. The transmissionoperation unit 57 is configured to communicate with an electroniccontrol unit 92 of the bicycle controller 90. The transmission operationunit 57 is configured to communicate with the electronic control unit 92through a wire connection or a wireless connection. The transmissionoperation unit 57 is configured to communicate with the electroniccontrol unit 92 through, for example, Power Line Communication (PLC).The rider operates the transmission operation unit 57. As a result, thetransmission operation unit 57 transmits an output signal to theelectronic control unit 92. The output signal can be a shift-up signalthat increases the ratio R of the bicycle 10 or a shift-down signal thatdecreases the ratio R of the bicycle 10. The transmission operation unitincludes, for example, an operation member, a sensor, and an electriccircuit (none shown). The sensor detects movement of the operationmember, and the electric circuit communicates with the electroniccontrol unit 92 in accordance with the output signal of the sensor.

The motor 54 and a drive circuit 68 form the assist device A. The drivecircuit 68 controls the power supplied from the battery unit 60 to themotor 54. The motor 54 assists the propulsion of the bicycle 10. Themotor 54 includes an electric motor. The motor 54 transmits rotation tothe transmission path L of the manual driving force TA from the pedals28 to the wheel 14.

As shown in FIG. 2, the motor 54 transmits output torque TM of the motor54 to the output portion 30. The power transmission path between themotor 54 and the crankshaft 38 includes the clutch 56 so that therotation force of the crank 26 does not rotate the motor 54 in a case inwhich the crankshaft 38 rotates in the direction in which the bicycle 10moves forward. The assist device A can include a structure other thanthe motor 54 and the drive circuit 68. For example, the assist device Acan include a reduction gear that reduces the speed of the rotationproduced by the motor 54 before outputting the rotation. In one example,the clutch 56 is located between the crank 26 and the output portion 30.

The transmission path L will now be described. The motor 54 transmitsthe output torque TM to the upstream side of the transmission device 52in the transmission path L. The manual driving force TA input to thecrank 26 is transmitted to the output portion 30. The output torque TMof the motor 54 is transmitted to the output portion 30. The manualdriving force TA is combined with the output torque TM of the motor 54at the output portion 30. The torque T combined at the output portion 30is input via the front rotation body 32 and the rear rotation body 34 tothe transmission device 52. The transmission device 52 changes the speedof the torque T with a predetermined gear and then outputs the torque Tto the wheel 14. In a case in which the bicycle 10 moves forward, theclutch 56 interrupts transmission of the rotation produced by the motor54 to the crank 26. In one example, the clutch 56 includes a one-wayclutch. The clutch 56 can be omitted.

As shown in FIG. 4, the operation device 58 is attached to the handlebar24. The operation device 58 is configured to communicate with theelectronic control unit 92 of the bicycle controller 90 (refer to FIG.3) through wire connection or wireless connection. The operation device58 is configured to communicate with the electronic control unit 92through, for example, PLC. The operation device 58 includes a firstswitch 74, a second switch 76 and a display 78. In a case in which thefirst switch 74 is operated, the operation device 58 transmits a firstsignal to the electronic control unit 92. In a case in which the secondswitch 76 is operated, the operation device 58 transmits a second signalto the electronic control unit 92. The display 78 shows operation modesof the motor 54. The operation mode includes a first mode and a secondmode. The display 78 can be arranged independently from the operationdevice 58 or be omitted. The first switch 74 and the second switch 76can each include, for example, a push-button switch. The first switch 74and the second switch 76 can have any form as long as it is operable bythe rider. At least one of the first switch 74 and the second switch 76can be replaced by, for example, a lever.

As shown in FIG. 1, the battery unit 60 includes a battery 80 and abattery holder 82. The battery holder 82, which is fixed to the frame20, holds the battery 80 in a removable manner. The battery 80 includesone or more battery cells. The battery 80 includes a rechargeablebattery. The battery 80 supplies power to other electric components(e.g., the motor 54, the actuator 70 and the bicycle controller 90) thatare electrically connected by wires to the battery 80.

Referring to FIG. 3, the torque sensor 62 outputs a signal correspondingto the manual driving force TA. The torque sensor 62 detects the manualdriving force TA applied to the crankshaft 38. The torque sensor 62 canbe arranged anywhere between the crankshaft 38 and the front rotationbody 32. For example, the torque sensor 62 can be arranged on thecrankshaft 38 or the front rotation body 32 or on the crank arms 40 orthe pedals 28. The torque sensor 62 can be realized using, for example,a strain gauge, a magnetostrictive sensor, an optical sensor, or apressure sensor. Further, any sensor can be used as the torque sensor 62as long as it outputs a signal that corresponds to the manual drivingforce TA applied to the crank arms 40 or the pedals 28.

The rotational angle sensor 64 detects a crank rotational angle CA. Therotational angle sensor 64 is attached to the frame 20 of the bicycle 10or the housing 72 of the assist device A. The rotational angle sensor 64includes a first element 64A that detects the magnetic field of a firstmagnet M1 and a second element 64B that outputs a signal correspondingto the positional relationship with a second magnet M2. The first magnetM1 is arranged on the crankshaft 38 or the crank arms 40 coaxially withthe crankshaft 38. The first magnet M1 is an annular magnet, and hasmultiple magnetic poles that are alternately arranged in thecircumferential direction. The first element 64A detects the rotationalangle of the crank 26 relative to the frame 20. Whenever the crank 26rotates once, the first element 64A outputs a signal of which singlecycle is an angle obtained by dividing 360 degrees by the number ofmagnetic poles having the same polarity. The minimum value of therotational angle of the crank 26 that is detectable by the rotationalangle sensor 64 is 180 degrees or less, preferably, 15 degrees, and morepreferably, 6 degrees. The second magnet M2 is arranged on thecrankshaft 38 or the crank arms 40. The second element 64B detects areference angle of the crank 26 relative to the frame (e.g., top deadcenter or bottom dead center of crank 26). The second element 64Boutputs a signal of which single cycle is a single rotation of thecrankshaft 38.

The rotational angle sensor 64 can be configured to include a magneticsensor, which outputs a signal corresponding to the intensity of themagnetic field, instead of the first element 64A and the second element64B. In this case, an annular magnet of which the intensity of themagnetic field changes in the circumferential direction is arranged inlieu of the first magnet M1 and the second magnet M2 on the crankshaft38 coaxially with the crankshaft 38. The use of a magnetic sensor thatoutputs a signal corresponding to the intensity of the magnetic fieldallows a crank rotational speed CN and the rotational angle CA of thecrank 26 to be detected with a single sensor. This simplifies thestructure and facilitates assembling. In addition to the crankrotational angle CA, the rotational angle sensor 64 can detect a crankrotational speed N. The crank rotational speed N can be detected usingany one of the output of the first element 64A, the output of the secondelement 64B, and the output of the magnetic sensor. The rotational anglesensor 64 can be omitted.

The vehicle speed sensor 66 is electrically connected to the electroniccontrol unit 92 through a wire connection or a wireless connection. Thevehicle speed sensor 66 is attached to a chain stay of the frame 20shown in FIG. 1. The vehicle speed sensor 66 outputs a signal to theelectronic control unit 92 that corresponds to changes in the positionrelative to a magnet 88 attached to a spoke 14B of the rear wheel 14. Itis preferred that the vehicle speed sensor 66 include a magnetic reed,which forms a reed switch, or a Hall element.

The bicycle controller 90 includes the electronic control unit 92. Inone example, it is further preferred that the bicycle controller 90include a memory 94 (i.e., computer data storage device). The electroniccontrol unit 92 includes an arithmetic processing unit that executespredetermined control programs. The arithmetic processing unit caninclude, for example, a Central Processing Unit (CPU) or a MicroProcessing Unit (MPU). The electronic control unit 92 can include one ormore microcomputers. The memory 94 stores information used for varioustypes of control programs and various types of control processes. Thememory 94 includes, for example, a non-volatile memory and a volatilememory.

The electronic control unit 92 controls the transmission device 52 andthe motor 54. The electronic control unit 92 is configured to beswitched between a first mode and a second mode. In the first mode, theelectronic control unit 92 is configured to drive the motor 54 inaccordance with the manual driving force TA. The first mode includesmultiple assist modes and an off mode. The ratio of the output of themotor 54 to the manual driving force TA (hereinafter referred to as “theassist ratio”) differs in each assist mode. The motor 54 is not drivenin the off mode. In a case in which the first switch 74 of the operationdevice 58 is operated in the off mode, the electronic control unit 92switches to the assist mode having the lowest assist ratio. In a case inwhich the first switch 74 of the operation device 58 is operated withthe electronic control unit 92 in an assist mode, the electronic controlunit 92 switches to the mode having the assist ratio that is one stagehigher. In a case in which the first switch 74 of the operation device58 is operated with the electronic control unit 92 in the assist modehaving the highest assist ratio, the electronic control unit 92 remainsin the assist mode having the highest assist ratio. In a case in whichthe second switch 76 of the operation device 58 is operated in the offmode, the electronic control unit 92 switches from the first mode to thesecond mode. In a case in which the second switch 76 of the operationdevice 58 is operated with the electronic control unit 92 in an assistmode, the electronic control unit 92 switches to the mode having theassist ratio that is one stage lower. In a case in which the secondswitch 76 of the operation device 58 is operated with the electroniccontrol unit 92 in the assist mode having the lowest assist ratio, theelectronic control unit 92 switches to the off mode. The first mode canbe configured to include one assist mode and an off mode or include onlyone assist mode.

In the second mode, the electronic control unit 92 is configured todrive the motor 54 and assist movement of the bicycle 10 while a riderwalks and pushes the bicycle 10. The second mode includes a standby modethat does not drive the motor 54 and a drive mode that drives the motor54. When shifted from the first mode to the second mode, the electroniccontrol unit 92 enters the standby mode. In a case in which the secondswitch 76 is operated in the standby mode, the electronic control unit92 switches from the standby mode to the drive mode. As long as there isno need to stop driving the motor 54 in accordance with inputs from thesensor or as long as the first switch 74 or the transmission operationunit 57 is not operated, continuous pushing of the second switch 76 inthe second mode maintains the drive mode and drives the motor 54. In astate in which the second switch 76 is being operated to maintain thedrive mode, by releasing the second switch 76, the electronic controlunit 92 switches from the drive mode to the standby mode. In a state inwhich the second switch 76 is being operated to maintain the drive mode,if there is a need to stop the motor 54 in accordance with inputs fromsensors or if the first switch 74 or the transmission operation unit 57is operated, then the electronic control unit 92 switches from the drivemode to the standby mode. In a case in which the drive mode is switchedto the standby mode by operating the second switch 76, the electroniccontrol unit 92 can be switched again from the standby mode to the drivemode by releasing the second switch 76 and then operating the secondswitch 76 again.

The electronic control unit 92 is configured to control the transmissiondevice 52 and change the ratio R in order to switch between the firstmode and the second mode. To switch from the first mode to the secondmode, the electronic control unit 92 controls the transmission device 52to decrease the ratio R. In the second mode, the electronic control unit92 controls the transmission device 52 so that the ratio R becomes lessthan or equal to a predetermined first ratio R1. In a case in which theoperation device 58 is operated to stop the motor in the second mode,the electronic control unit 92 controls the transmission device 52 sothat the ratio R becomes less than or equal to a predetermined secondratio R2. The electronic control unit 92 is configured to drive themotor 54 during the second mode in a case in which the manual drivingforce TA is not input to the crank 26.

A switching control for switching between the first mode and the secondmode will now be described with reference to FIG. 5. The electroniccontrol unit 92 executes the switching control in predetermined cyclesas long as the bicycle controller 90 is supplied with power. If thesupply of power is cut, then the bicycle controller 90 stops executingthe switching control.

In step S11, the electronic control unit 92 determines whether or notthe present mode is the first mode. If the electronic control unit 92determines that the present mode is the first mode in step S11, then theelectronic control unit 92 proceeds to step S12.

In step S12, the electronic control unit 92 determines whether or not anoperation for switching to the second mode has been performed. Morespecifically, in the off mode of the first mode, the electronic controlunit 92 determines that an operation for switching to the second modehas been performed if the second switch 76 of the operation device 58 isoperated. The electronic control unit 92 can also determine that anoperation for switching to the second mode has been performed during anassist mode in the first mode if the second switch 76 of the operationdevice 58 is operated or the second switch 76 of the operation device 58is operated for a predetermined time or longer.

If the electronic control unit 92 determines that an operation forswitching to the second mode has not been performed, then the electroniccontrol unit 92 terminates the processing and restarts the processingafter a predetermined cycle from step S11. If the electronic controlunit 92 determines that an operation for switching to the second modehas been performed, then the electronic control unit 92 proceeds to stepS13 and switches from the first mode to the second mode. Then, theelectronic control unit 92 proceeds to step S14.

In step S14, the electronic control unit 92 determines whether or notthe ratio R is greater than the first ratio R1. If the electroniccontrol unit 92 determines in step S14 that the ratio R is less than orequal to the first ratio R, then the electronic control unit 92terminates the processing and restarts the processing after apredetermined cycle from step S11. If the electronic control unit 92determines that the ratio R is greater than the first ratio R1, in stepS15, then the electronic control unit 92 controls the transmissiondevice 52 so that the ratio R becomes less than or equal to the firstratio R1. Then, the electronic control unit 92 terminates the processingand restarts the processing after a predetermined cycle from step S11.In one example, the electronic control unit 92 in step S15 controls thetransmission device 52 so that the ratio R becomes equal to the firstratio R1. As long as the first ratio R1 is not the minimum ratio R thatcan be realized by the transmission device 52, the electronic controlunit 92 can decrease the ratio R to be smaller than the first ratio R1.

If the electronic control unit 92 determines in step S11 that thepresent mode is not the first mode, that is, the present mode is thesecond mode, then the electronic control unit 92 proceeds to step S16and determines whether or not an operation for switching to the firstmode has been performed. More specifically, in the standby mode of thesecond mode, the electronic control unit 92 determines that an operationfor switching to the first mode has been performed if the first switch74 of the operation device 58 is operated. In the drive mode of thesecond mode, the electronic control unit 92 can determine that anoperation for switching to the first mode has been performed if thefirst switch 74 of the operation device 58 is operated or if the firstswitch 74 of the operation device 58 is operated for a predeterminedtime or longer. When the electronic control unit 92 determines that anoperation for switching to the first mode has not been performed, theelectronic control unit 92 terminates the processing and restarts theprocessing after a predetermined cycle from step S11. If the electroniccontrol unit 92 determines that an operation for switching to the firstmode has been performed, in step S17, then the electronic control unit92 switches from the second mode to the first mode. Then, the electroniccontrol unit 92 terminates the processing and restarts the processingafter a predetermined cycle from step S11.

A drive control of the motor 54 in the second mode will now be describedwith reference to FIG. 6. The electronic control unit 92 executes thedrive control in predetermined cycles as long as the bicycle controller90 is supplied with power. If the supply of power is cut, then thebicycle controller 90 stops executing the drive control.

In step S21, the electronic control unit 92 determines whether or notthe present mode is the second mode. If the electronic control unit 92determines that the present mode is the second mode, in step S22, theelectronic control unit 92 determines whether or not an operation fordriving the motor 54 has been performed. More specifically, if thesecond switch 76 has been operated in the standby state, then theelectronic control unit 92 determines that an operation for driving themotor 54 has been performed.

If the electronic control unit 92 determines in step S22 that anoperation for driving the motor 54 has been performed, then theelectronic control unit 92 proceeds to step S23 and determines whetheror not there is no input of the manual driving force TA. Morespecifically, the electronic control unit 92 determines that the manualdriving force TA is not being inputted when the manual driving force TAdetected by the torque sensor 62 is less than or equal to adetermination value TX. Preferably, the determination value TX is “0.”If the electronic control unit 92 determines in step S23 that the manualdriving force TA is being input, then the electronic control unit 92does not drive the motor 54 and restarts the processing after apredetermined cycle from step S21. If the electronic control unit 92determines that the manual driving force TA is not being inputted, thenthe electronic control unit 92 proceeds to step S24 and drives the motor54. The electronic control unit 92 then restarts the processing after apredetermined cycle from step S21.

If the electronic control unit 92 determines in step S22 that anoperation for driving the motor 54 has not been performed, then theelectronic control unit 92 proceeds to step S25. More specifically, theelectronic control unit 92 determines that an operation for driving themotor 54 has not been performed if the second switch 76 has not beenoperated. In step S25, the electronic control unit 92 determines whetheror not a stopping operation has been performed on the motor 54. In oneexample, the stopping operation includes releasing the second switch 76.More specifically, the electronic control unit 92 determines that astopping operation has been performed on the motor 54 if the secondswitch 76 was operated in the previous drive control cycle but not inthe present drive control cycle. If the electronic control unit 92determines that a stopping operation has not been performed on the motor54, then the electronic control unit 92 terminates the processing andrestarts the processing after a predetermined cycle from step S21. Ifthe electronic control unit 92 determines that a stopping operation hasbeen performed on the motor 54, then the electronic control unit 92proceeds to step S26.

In step S26, the electronic control unit 92 determines whether or notthe ratio R is greater than the second ratio R2. If the electroniccontrol unit 92 determines that the ratio R is less than or equal to thesecond ratio R2, then the electronic control unit 92 terminates theprocessing and restarts the processing after a predetermined cycle fromstep S21. If the electronic control unit 92 determines that the ratio Ris greater than the second ratio R2, then the electronic control unit 92proceeds to step S27 and controls the transmission device 52 so that theratio R becomes less than or equal to the second ratio R2 and restartsthe processing after a predetermined cycle from step S21. Preferably,the electronic control unit 92 controls the transmission device 52 instep S27 so that the ratio R becomes equal to the second ratio R2. Whenthe second ratio R2 is not the minimum ratio R that can be realized bythe transmission device 52, the electronic control unit 92 can decreasethe ratio R to be smaller than the second ratio R2. The second ratio R2can be equal to or different from the first ratio R1.

In the drive control of the first embodiment, steps S25 to S27 can beomitted. If steps S25 to S27 are omitted and the electronic control unit92 determines in step S22 that an operation for driving the motor 54 hasnot been performed, the electronic control unit 92 terminates theprocessing.

Second Embodiment

The bicycle controller 90 of a second embodiment will now be describedwith reference to FIGS. 3, 7 and 8. The bicycle controller 90 of thesecond embodiment only differs from the bicycle controller 90 of thefirst embodiment in the processing executed by the electronic controlunit 92. Same reference numerals are given to those elements that arethe same as the corresponding elements of the first embodiment. Suchelements will not be described below. The second embodiment differs fromthe first embodiment in the conditions for changing the ratio R in thesecond mode.

The electronic control unit 92 is configured to change the ratio R bycontrolling the transmission device 52. When an operation for drivingthe motor 54 is performed on the operation device 58 in the second mode,the electronic control unit 92 drives the motor 54 and controls thetransmission device 52 to decrease the ratio R.

The switching control of the second embodiment will now be describedwith reference to FIG. 7. In the switching control of the secondembodiment, steps S14 an S15 are omitted from the switching controlflowchart of FIG. 5. Steps S11, S12, S13, S16 and S17 of the switchingcontrol in the second embodiment are processes that are respectivelyidentical to steps S11, S12, S13, S16 and S17 of the switching controlin the first embodiment shown in FIG. 5 and executed in the same order.

If the electronic control unit 92 determines in step S12 that anoperation for switching to the second mode has been performed, then theelectronic control unit 92 proceeds to step S13 and switches from thefirst mode to the second mode. Then, the electronic control unit 92terminates the processing and restarts the processing after apredetermined cycle from step S11.

A drive control in the second mode will now be described with referenceto FIG. 8. In the drive control of the second embodiment, step S14 orsteps S14 and S15 are performed after step S24. Steps S21, S22, S23,S24, S25, S26 and S27 of the drive control in the second embodiment areprocesses that are respectively identical to steps S21, S22, S23, S24,S25, S26 and S27 of the drive control in the first embodiment shown inFIG. 6 and executed in the same order.

In step S24, the electronic control unit 92 drives the motor 54 and thenproceeds to step S14. The electronic control unit 92 in step S14determines whether or not the ratio R is greater than the first ratioR1. If the electronic control unit 92 determines that the ratio R isless than or equal to the first ratio R1, then the electronic controlunit 92 terminates the processing and restarts the processing after apredetermined cycle from step S21. If the electronic control unit 92determines that the ratio R is greater than the first ratio R1, then theelectronic control unit 92 proceeds to step S15 and controls thetransmission device 52 so that the ratio R becomes less than or equal tothe first ratio R1. Then, the electronic control unit 92 terminates theprocessing and restarts the processing after a predetermined cycle fromstep S11.

In the drive control of the second embodiment, steps S25 to S27 or stepsS14 and S15 can be omitted. If steps S25 to S27 are omitted and theelectronic control unit 92 determines in step S22 that an operation fordriving the motor 54 has not been performed, the electronic control unit92 terminates the processing.

Third Embodiment

The bicycle controller 90 of a third embodiment will now be describedwith reference to FIGS. 3 and 9. The bicycle controller 90 of the thirdembodiment differs from the bicycle controller 90 of the secondembodiment only in the processing executed by the electronic controlunit 92. Same reference numerals are given to those elements that arethe same as the corresponding elements of the second embodiment. Suchelements will not be described below. The third embodiment differs fromthe second embodiment in the conditions for changing the ratio R in thesecond mode.

If the output torque TM of the motor 54 becomes greater than or equal toa predetermined torque TMX in the second mode, the electronic controlunit 92 controls the transmission device 52 to decrease the ratio R. Theelectronic control unit 92 controls the rotational speed N of the motor54 in accordance with the ratio R in the second mode. To change theratio R with the transmission device 52, the electronic control unit 92controls the rotational speed N of the motor 54 so that the differencebetween a vehicle speed V before changing the ratio R and the vehiclespeed V after changing the ratio R becomes less than or equal to apredetermined value DV. The electronic control unit 92 controls therotational speed N of the motor 54 in accordance with the ratio R in thesecond mode.

A drive control in the second mode will now be described with referenceto FIG. 9. The electronic control unit 92 executes the drive control inpredetermined cycles as long as the bicycle controller 90 is suppliedwith power. If the supply of power is cut, the bicycle controller 90stops executing the drive control.

Steps S21, S22, S23, S24, S25, S26 and S27 of the drive control in thethird embodiment are respectively identical to steps S21, S22, S23, S24,S25, S26 and S27 of the drive control in the second embodiment shown inFIG. 8 and executed in the same order.

In step S24, if the electronic control unit 92 drives the motor 54, thenthe electronic control unit 92 proceeds to step S31 and determineswhether or not the output torque TM of the motor 54 is greater than orequal to the predetermined torque TMX. If the electronic control unit 92determines that the output torque TM of the motor 54 is less than thepredetermined torque TMX, then the electronic control unit 92 terminatesthe processing and restarts the processing after a predetermined cyclefrom step S21. The electronic control unit 92 detects the output torqueTM of the motor 54 from a command that operates the motor 54 or from thecurrent flowing to the motor 54. If the electronic control unit 92determines in step S31 that the output torque TM of the motor 54 isgreater than or equal to the predetermined torque TMX, then theelectronic control unit 92 proceeds to step S14 and determines whetheror not the ratio R is greater than the first ratio R1. If the electroniccontrol unit 92 determines that the ratio R is less than or equal to thefirst ratio R1, then the electronic control unit 92 terminates theprocessing and restarts the processing after a predetermined cycle fromstep S21. If the electronic control unit 92 determines that the ratio Ris greater than the first ratio R1, then the electronic control unit 92proceeds to step S15 and controls the transmission device 52 so that theratio R becomes less than or equal to the first ratio R1. Then, theelectronic control unit 92 proceeds to step S32.

In step S32, the electronic control unit 92 controls the rotationalspeed N of the motor 54 in accordance with the ratio R. Morespecifically, the electronic control unit 92 controls the rotationalspeed N of the motor 54 so that the difference between the vehicle speedV before the ratio R was changed and the vehicle speed V after the ratioR was changed becomes lower than or equal to the predetermined value DV.The memory 94 of the present embodiment stores in advance a map or atable showing the relationship of the ratio R and the rotational speedN. The electronic control unit 92 controls the rotational speed N of themotor 54 based on the map or table stored in the memory 94. The memory94 can store a function instead of the map or table. The relationship ofthe ratio R and the rotational speed N is set so that the rotationalspeed N increases as the ratio R decreases. The relationship of theratio R and the rotational speed N is set so that the rotational speedof the wheel 14 falls within a predetermined range or becomes constant.In a case in which the rotational speed N of the motor 54 is constant, adecrease in the ratio R will decrease the rotational speed of the wheel14. Thus, if the electronic control unit 92 decreases the ratio R, thenthe electronic control unit 92 will increase the rotational speed N ofthe motor 54 so that the rotational speed of the wheel 14 approaches therotational speed before the ratio R was changed for the differencebetween the vehicle speed V before the ratio R was changed and thevehicle speed V after the ratio R was changed to become less than orequal to the predetermined value DV. If the electronic control unit 92increases the ratio R, the electronic control unit 92 will decrease therotational speed N of the motor 54 so that the rotational speed of thewheel 14 approaches the rotational speed before the ratio R was changedin for the difference between the vehicle speed V before the ratio R waschanged and the vehicle speed V after the ratio R was changed to becomeless than or equal to the predetermined value DV. After processing stepS32, the electronic control unit 92 restarts the processing after apredetermined cycle from step S21. Instead of the relationship betweenthe ratio R and the rotational speed N, the memory 94 can store therelationship between the gears and the rotational speed N. In this case,the memory 94 stores the motor rotational speed N corresponding to eachgear. One of steps S31 and S32 can be omitted from the drive control inthe third embodiment.

Fourth Embodiment

The bicycle controller 90 of a fourth embodiment will now be describedwith reference to FIGS. 3 and 10. The bicycle controller 90 of thefourth embodiment basically differs from the bicycle controller 90 ofthe first embodiment in the processing executed by the electroniccontrol unit 92. Same reference numerals are given to those elementsthat are the same as the corresponding elements of the first embodiment.Such elements will not be described below. In the fourth embodiment, theelectronic control unit 92 executes the switching-drive control shown inFIG. 10 instead of the switching control shown in FIG. 5 and the drivecontrol shown in FIG. 6.

If an operation for driving the motor 54 is performed on the operationdevice 58 in the first mode, then the electronic control unit 92switches from the first mode to the second mode to drive the motor 54and control the transmission device 52 in order to decrease the ratio R.If the electronic control unit 92 switches from the second mode to thefirst mode, then the electronic control unit 92 controls thetransmission device 52 to decrease the ratio R. The operation fordriving the motor 54 includes, for example, operating one of the firstswitch 74 and the second switch 76 of the operation device 58 for apredetermined time or longer. In addition to or instead of the firstswitch 74 and the second switch 76, the operation device 58 can includea third switch (not shown). In this case, the operation for driving themotor 54 can include, for example, operating the third switch of theoperation device 58.

The switching-drive control that switches the first mode and the secondmode and drives the motor 54 will now be described with reference toFIG. 10. The electronic control unit 92 executes the switching-drivecontrol in predetermined cycles as long as the bicycle controller 90 issupplied with power. If the supply of power is cut, the bicyclecontroller 90 stops executing the switching-drive control.

In step S41, the electronic control unit 92 determines whether or notthe present mode is the first mode. If the electronic control unit 92determines that the present mode is not the first mode, then theelectronic control unit 92 terminates the processing and restarts theprocessing after a predetermined cycle from step S41. If the electroniccontrol unit 92 determines in step S41 that the present mode is thefirst mode, then the electronic control unit 92 proceeds to step S42.

In step S42, the electronic control unit 92 determines whether or not anoperation for driving the motor 54 has been performed. If the electroniccontrol unit 92 determines in step S42 that an operation for driving themotor 54 has not been performed, then the electronic control unit 92terminates the processing and restarts the processing after apredetermined cycle from step S41. If the electronic control unit 92determines in step S42 that an operation for driving the motor 54 hasbeen performed, then the electronic control unit 92 proceeds to step S43and switches from the first mode to the second mode. Then, theelectronic control unit 92 proceeds to step S44. The electronic controlunit 92 determines that an operation for driving the motor 54 has beenperformed if the first switch 74 or the second switch 76 of theoperation device 58 is operated for a predetermined time or long or ifthe third switch is operated. In step S44, the electronic control unit92 determines whether or not there is no input of the manual drivingforce TA. If the electronic control unit 92 determines in step S44 thatthe manual driving force TA is being input, the electronic control unit92 proceeds to step S48 without controlling the motor 54 and thetransmission device 52. If the electronic control unit 92 determines instep S44 that the manual driving force TA is not being inputted, thenthe electronic control unit 92 proceeds to step S45 and drives the motor54. Then, the electronic control unit 92 proceeds to step S46.

In step S46, the electronic control unit 92 determines whether or notthe ratio R is greater than the first ratio R1. When the electroniccontrol unit 92 determines in step S46 that the ratio R is less than orequal to the first ratio R1, the electronic control unit 92 proceeds tostep S48 without controlling the transmission device 52. If theelectronic control unit 92 determines in step S46 that the ratio R isgreater than the first ratio R1, then the electronic control unit 92proceeds to step S47. In step S47, the electronic control unit 92controls the transmission device 52 so that the ratio R becomes lessthan or equal to the first ratio R1. Then, the electronic control unit92 proceeds to step S48.

The electronic control unit 92 determines in step S48 whether or not anoperation for stopping the motor 54 has been performed. The electroniccontrol unit 92 determines that an operation for stopping the motor 54has been performed if the first switch 74 or the second switch 76, whichhas been operated for a predetermined time or longer, is released or ifthe third switch is released. If the electronic control unit 92determines that an operation for stopping the motor 54 has not beenperformed, then the electronic control unit 92 executes the processes ofsteps S44 to S47 again. That is, the electronic control unit 92continues to drive the motor 54 in accordance with the manual drivingforce TA until an operation for stopping the motor 54 is performed.

If the electronic control unit 92 determines in step S48 that anoperation for stopping the motor 54 has been performed, then theelectronic control unit 92 proceeds to step S49 and switches from thesecond mode to the first mode. Then, the electronic control unit 92proceeds to step S50 and determines whether or not the ratio R isgreater than the second ratio R2. If the electronic control unit 92determines that the ratio R is less than or equal to the second ratio R,then the electronic control unit 92 terminates the processing andrestarts the processing after a predetermined cycle from step S41. Ifthe electronic control unit 92 determines that the ratio R is greaterthan the second ratio R2, the electronic control unit 92 proceeds tostep S51 and controls the transmission device 52 so that the ratio Rbecomes less than or equal to the second ratio R2 and restarts theprocessing after a predetermined cycle from step S41. In the fourthembodiment, the electronic control unit 920 is able to immediately shiftto the second mode and drive the motor 54 from any assist mode. Step S44can be omitted from the switching-drive control of the fourthembodiment. Further, steps S46 and S47 or steps S50 and S51 can beomitted from the switching-drive control of the fourth embodiment.

Fifth Embodiment

The bicycle controller 90 of a fifth embodiment will now be describedwith reference to FIGS. 3, 11, and 12. The bicycle controller 90 of thefifth embodiment differs from the bicycle controller 90 of the firstembodiment in the processing executed by the electronic control unit 92.Same reference numerals are given to those elements that are the same asthe corresponding elements of the first embodiment. Such elements willnot be described below. In the fifth embodiment, the electronic controlunit 92 executes a switching control that includes steps S26 and S27 ofthe drive control in the first embodiment (refer to FIG. 6).

The electronic control unit 92 controls the transmission device 52 sothat the ratio R decreases if the electronic control unit 92 switchesfrom the second mode to the first mode.

The switching control will now be described with reference to FIG. 11.Steps S11, S12, S13, S14, S15, S16 and S17 of the switching control ofthe motor 54 in the fifth embodiment are respectively identical to stepsS11, S12, S13, S14, S15, S16 and S17 of the switching control in thefirst embodiment shown in FIG. 5 and executed in the same order.

If the electronic control unit 92 is switched to the first mode in stepS17, then the electronic control unit 92 proceeds to step S26 anddetermines whether or not the ratio R is greater than the second ratioR2. If the electronic control unit 92 determines that the ratio R isless than or equal to the second ratio R2, then the electronic controlunit 92 terminates the processing and restarts the processing after apredetermined cycle from step S11. If the electronic control unit 92determines that the ratio R is greater than the second ratio R2, thenthe electronic control unit 92 proceeds to step S27 and controls thetransmission device 52 so that the ratio R becomes less than or equal tothe second ratio R2. Then, the electronic control unit 92 terminates theprocessing and restarts the processing after a predetermined cycle fromstep S11.

The drive control will now be described with reference to FIG. 12. StepsS21, S22, S23, S24, and S25 of the drive control in the fifth embodimentare respectively identical to steps S21, S22, S23, S24 and S25 of thedrive control in the first embodiment shown in FIG. 6 and executed inthe same order. If the electronic control unit 92 determines in step S25that an operation for stopping the motor 54 has been performed, then theelectronic control unit 92 terminates the processing and restarts theprocessing after a predetermined cycle from step S21. Steps S14 and S15can be omitted from the switching control of the fifth embodiment.

Sixth Embodiment

The bicycle controller 90 of the sixth embodiment will now be describedwith reference to FIGS. 3 and 13. The bicycle controller 90 of the sixthembodiment differs from the bicycle controller 90 of the secondembodiment only in the processing executed by the electronic controlunit 92. Same reference numerals are given to those elements that arethe same as the corresponding elements of the second embodiment. Suchelements will not be described below. The sixth embodiment differs fromthe second embodiment in the timing in which the ratio R is changed inthe second mode.

The electronic control unit 92 controls the transmission device 52 inaccordance with the vehicle speed V in the second mode. If the vehiclespeed V is less than or equal to a predetermined vehicle speed VX in thesecond mode, then the electronic control unit 92 controls thetransmission device 52 to increase the ratio R.

The drive control of the motor 54 in the second mode will now bedescribed with reference to FIG. 13. Steps S21, S22, S23, S24, S25, S26and S27 of the drive control in the sixth embodiment are respectivelyidentical to steps S21, S22, S23, S24, S25, S26 and S27 of the drivecontrol in the second embodiment shown in FIG. 8 and executed in thesame order.

The electronic control unit 92 drives the motor 54 in step S24. Then, instep S71, the electronic control unit 92 determines whether or not thevehicle speed V is less than or equal to the vehicle speed VX. If theelectronic control unit 92 determines that the vehicle speed V isgreater than the predetermined vehicle speed VX, then the electroniccontrol unit 92 terminates the processing and restarts the processingafter a predetermined cycle from step S21. If the electronic controlunit 92 determines that the vehicle speed V is less than or equal to thepredetermined vehicle speed VX in step S71, then the electronic controlunit 92 proceeds to step S72 and controls the transmission device 52 toincrease the ratio R. If the present ratio R is the maximum ratio R, theelectronic control unit 92 maintains the present ratio R. Afterexecuting the process of step S72, the electronic control unit 92terminates the processing and restarts the processing after apredetermined cycle from step S21. The predetermined vehicle speed VX isset to, for example, 1 km/h. If the vehicle speed V becomes less thanthe predetermined vehicle speed VX while the rider is walking andpushing the bicycle 10, then the ratio R is increased. This avoidssituations in which the vehicle speed V becomes too slow while the rideris walking and pushing the bicycle 10.

Seventh Embodiment

The bicycle controller 90 of a seventh embodiment will now be describedwith reference to FIGS. 3 and 14. The bicycle controller 90 of theseventh embodiment differs from the bicycle controller 90 of the secondembodiment only in the processing executed by the electronic controlunit 92. Same reference numerals are given to those elements that arethe same as the corresponding elements of the second embodiment. Suchelements will not be described below. The seventh embodiment differsfrom the second embodiment in the conditions for changing the ratio R inthe second mode.

If the electronic control unit 92 detects slipping of the wheel 14 whiledriving the motor 54 in the second mode, then the electronic controlunit 92 controls the transmission device 52 to increase the ratio R. Ifthe electronic control unit 92 detects slipping of the wheel 14 whiledriving the motor 54 in the second mode, then the electronic controlunit 92 decreases the output torque TM of the motor 54.

The drive control in the second mode will now be described withreference to FIG. 14. Steps S21, S22, S23, S24, S25, S26 and S27 of thedrive control in the seventh embodiment are respectively identical tosteps S21, S22, S23, S24, S25, S26 and S27 of the drive control in thesecond embodiment shown in FIG. 8 and executed in the same order.

The electronic control unit 92 drives the motor 54 in step S24. Then, instep S81, the electronic control unit 92 determines whether or notslipping of the wheel 14 has been detected. In one example, theelectronic control unit 92 determines that slipping of the wheel 14 hasbeen detected if the electronic control unit 92 determines that therotational speed N of the motor 54, the rotational speed of the wheel14, or the rotational speed N of a rotation body included in thetransmission path L has suddenly increased. If the electronic controlunit 92 determines that slipping of the wheel 14 has not been detected,then the electronic control unit 92 terminates the processing andrestarts the processing after a predetermined cycle from step S21.

If the electronic control unit 92 determines that slipping of the wheel14 has been detected in step S81, the electronic control unit 92proceeds to step S82 and controls the transmission device 52 to increasethe ratio R. Then, the electronic control unit 92 proceeds to step S83.If the present ratio R is the maximum ratio R, then the electroniccontrol unit 92 maintains the present ratio R. In step S83, theelectronic control unit 92 decreases the output torque TM of the motor54. Subsequent to the execution of the process of step S83, theelectronic control unit 92 restarts the processing after a predeterminedcycle from step S21.

One of steps S82 and S83 can be omitted from the drive control of thesixth embodiment. Alternatively, step S82 and steps S25 to S27 can beomitted from the drive control of the sixth embodiment. As anotheroption, step S83 and steps S25 to S27 can be omitted from the drivecontrol of the sixth embodiment. As a further option, steps S25 to S27can be omitted from the drive control of the sixth embodiment.

Eighth Embodiment

The bicycle controller 90 of an eighth embodiment will now be describedwith reference to FIGS. 3 and 15. The bicycle controller 90 of theeighth embodiment differs from the bicycle controller 90 of the firstembodiment only in the processing executed by the electronic controlunit 92. Same reference numerals are given to those elements that arethe same as the corresponding elements of the second embodiment. Suchelements will not be described below. The eighth embodiment increasesthe ratio R if the electronic control unit 92 switches to the secondmode in the switching control. The electronic control unit 92 controlsthe transmission device 52 to increase the ratio R in a case in whichthe electronic control unit 92 switches from the first mode to thesecond mode.

The switching control will now be described with reference to FIG. 15.Steps S11, S12, S13, S16 and S17 of the switching control in the eighthembodiment are respectively identical to steps S11, S12, S13, S16 andS17 of the switching control of the motor 54 in the first embodimentshown in FIG. 5 and executed in the same order.

The electronic control unit 92 switches to the second mode in step S13.Then, the electronic control unit 92 proceeds to step S91 and determineswhether or not the ratio R is less than a third ratio R3. If theelectronic control unit 92 determines that the ratio R is greater thanor equal to the third ratio R3, then the electronic control unit 92terminates the processing and restarts the processing after apredetermined cycle from step S11. If the electronic control unit 92determines in step S91 that the ratio R is less than the third ratio R3,then the electronic control unit 92 proceeds to step S92. In step S92,the electronic control unit 92 controls the transmission device 52 sothat the ratio R becomes greater than or equal to the third ratio R3 andthen restarts the processing after a predetermined cycle from step S11.Preferably, the electronic control unit 92 controls the transmissiondevice 52 so that the ratio R becomes equal to the third ratio R3 instep S92. If the third ratio R3 is not the maximum ratio R that can berealized by the transmission device 52, then the electronic control unit92 can increase the ratio R so that the ratio R becomes greater than thethird ratio R3.

Ninth Embodiment

The bicycle controller 90 of a ninth embodiment will now be describedwith reference to FIGS. 3 and 16. The bicycle controller 90 of the ninthembodiment differs from the bicycle controller 90 of the secondembodiment only in the processing executed by the electronic controlunit 92. Same reference numerals are given to those elements that arethe same as the corresponding elements of the second embodiment. Suchelements will not be described below.

If an operation for driving the motor 54 is performed on the operationdevice 58 in the second mode, then the electronic control unit 92 drivesthe motor 54 and controls the transmission device 52 to increase theratio R. The drive control will now be described with reference to FIG.16.

Steps S21, S22, S23, S24, S25, S26 and S27 of the drive control in theninth embodiment are respectively identical to steps S21, S22, S23, S24,S25, S26 and S27 of the drive control in the second embodiment shown inFIG. 8 and executed in the same order.

If the electronic control unit 92 determines that there is no input ofthe manual driving force TA in step S23, the electronic control unit 92drives the motor 54 in step S24. Then, in step S91, the electroniccontrol unit 92 determines whether or not the ratio R is less than thethird ratio R3. If the electronic control unit 92 determines that theratio R is greater than or equal to the third ratio R3, then theelectronic control unit 92 terminates the processing and restarts theprocessing after a predetermined cycle from step S21. If the electroniccontrol unit 92 determines that the ratio R is less than the third ratioR3, then the electronic control unit 92 proceeds to step S92 andcontrols the transmission device 52 so that the ratio R becomes greaterthan or equal to the third ratio R3. Then, the electronic control unit92 terminates the processing and restarts the processing after apredetermined cycle from step S21. Steps S91 and S92 or steps S25 to S27can be omitted from the drive control of the ninth embodiment.

Tenth Embodiment

The bicycle controller 90 of the tenth embodiment will now be describedwith reference to FIGS. 3 and 17. The bicycle controller 90 of the tenthembodiment differs from the bicycle controller 90 of the fourthembodiment only in the processing executed by the electronic controlunit 92. Same reference numerals are given to those elements that arethe same as the corresponding elements of the fourth embodiment. Suchelements will not be described below.

If an operation for driving the motor 54 is performed on the operationdevice 58 in the first mode, then the electronic control unit 92switches from the first mode to the second mode, drives the motor 54,and controls the transmission device 52 to increase the ratio R.

In the switching control of the tenth embodiment, steps S91 and S92 areexecuted in lieu of steps S46 and S47 of the switching-drive control ofthe switching-drive control in the fourth embodiment shown in FIG. 10.Steps S41, S42, S43, S44, S45, S48, S49, S50 and S51 of theswitching-drive control in the tenth embodiment are respectivelyidentical to steps S41, S42, S43, S44, S45, S48, S49, S50 and S51 of theswitching-drive control in the fourth embodiment shown in FIG. 10 andexecuted in the same order.

If the electronic control unit 92 drives the motor 54 in step S45, thenthe electronic control unit 92 proceeds to step S91. In step S91, theelectronic control unit 92 determines whether or not the ratio R is lessthan the third ratio R3. If the electronic control unit 92 determinesthat the ratio R is greater than or equal to the third ratio R3, thenthe electronic control unit 92 proceeds to step S48. If the electroniccontrol unit 92 determines that the ratio R is less than the third ratioR3, then the electronic control unit 92 proceeds to step S92 andcontrols the transmission device 52 so that the ratio R becomes greaterthan or equal to the third ratio R3. Then, the electronic control unit92 proceeds to step S48.

MODIFIED EXAMPLES

It should be apparent to those skilled in the art that the presentinvention may be embodied in many other specific forms without departingfrom the spirit or scope of the invention. For example, some of thecomponents can be omitted from the components described in theembodiments (or one or more forms of the embodiments). Further,components in different embodiments can be appropriately combined. Thescope of the present invention and equivalence of the present inventionare to be understood with reference to the appended claims.

Step S31 of the drive control in the third embodiment shown in FIG. 9can be modified as described below. The electronic control unit 92determines whether or not the output torque TM of the motor 54 has beenheld at a maximum value of the output torque which is set to the motor54. If, the electronic control unit 92 determines that the output torqueTM of the motor 54 has been held at the maximum value of the outputtorque, then the electronic control unit 92 proceeds to step S14. If theelectronic control unit 92 determines that the output torque TM of themotor 54 has not been held at the maximum value of the output torque,the electronic control unit 92 terminates the processing and restartsthe processing after a predetermined cycle from step S21.

The drive control of the third embodiment shown in FIG. 9 can bemodified to the drive control shown in FIG. 18. The electronic controlunit 92 is configured to be switched between the first mode, whichcontrols the motor 54 in accordance with the manual driving force TA,and the second mode, which allows the motor 54 to be controlled so thatthe bicycle can be moved. The electronic control unit 92 controls therotational speed N of the motor 54 in accordance with the vehicle speedV in the second mode. More specifically, the electronic control unit 92executes the process of step S100 in FIG. 18 instead of the process ofstep S32 in FIG. 9. In step S15, the electronic control unit 92 controlsthe transmission device 52 so that the vehicle speed V becomes less thanor equal to a first speed V 1. Then, the electronic control unit 92proceeds to step S100 and controls the rotational speed N of the motor54 in accordance with the vehicle speed V. More specifically, therotational speed N of the motor 54 is increased as the vehicle speed Vdecreases.

If the electronic control unit 92 switches between the first mode andthe second mode or is in the second mode in the first to fifthembodiments, then the electronic control unit 92 can control thetransmission device 52 so that the ratio R becomes equal to a firstpredetermined ratio RA. More specifically, step S14 can be omitted fromthe first to third and fifth embodiments and step S46 can be omittedfrom the fourth embodiment. In this case, instead of the process of stepS15 in the first to third and fifth embodiments and the process of stepS47 in the fourth embodiment, the electronic control unit 92 performs aprocess for controlling the transmission device 52 so that the ratio Rbecomes equal to the first predetermined ratio RA, which is stored inadvance in the memory 94.

If the electronic control unit 92 switches between the first mode andthe second mode or is in the first mode in each embodiment, then theelectronic control unit 92 can control the transmission device 52 sothat the ratio R becomes equal to a second predetermined ratio RB. Morespecifically, step S26 can be omitted from the first to third and fifthembodiments and step S50 can be omitted from the fourth embodiment. Inthis case, instead of the process of step S27 in the first to third andfifth embodiments and step S51 of the fourth embodiment, the electroniccontrol unit 92 performs a process for controlling the transmissiondevice 52 so that the ratio R becomes equal to the second predeterminedratio RB, which is stored in advance in the memory 94.

If the electronic control unit 92 switches between the first mode andthe second mode or is in the second in the eighth to tenth embodiments,then the electronic control unit 92 can control the transmission device52 so that the ratio R becomes equal to the third predetermined ratioRC. More specifically, step S91 can be omitted from the eighth to tenthembodiments. In this case, instead of the process of step S92 of theeighth to tenth embodiments, the electronic control unit 92 performs aprocess for controlling the transmission device 52 so that the ratio Rbecomes equal to the third predetermined ratio RC, which is stored inadvance in the memory 94.

In step S81 of the driving process in the seventh embodiment shown inFIG. 14, if the electronic control unit 92 detects slipping of the wheel14, then the electronic control unit 92 can further perform at least oneof reducing the speed of the bicycle 10 with an electric brake andreducing the speed of the motor 54.

As shown in FIG. 19, in each embodiment, the transmission device 52 caninclude an external transmission device (derailleur). The transmissiondevice 52 changes the speed of the rotation input to the crankshaft 38and transmits the rotation to the wheel 14 by moving the chain 36between a plurality of front rotation bodies 32 or a plurality of rearrotation bodies 34. The transmission device 52 includes at least one ofa front derailleur 52F and a rear derailleur 52R. The front derailleur52F moves the chain 36 (refer to FIG. 1) between the front rotationbodies 32. The rear derailleur 52R moves the chain 36 between the rearrotation bodies 34. If the transmission device 52 includes a derailleur,then the speed-changing operation includes moving the chain 36 betweenthe rotation bodies 32 and 34. The transmission device 52 can includeboth of an internal transmission device and a derailleur.

In each embodiment, the electronic control unit 92 can operate thetransmission device 52 in accordance with the state of the bicycle 10 orthe riding environment. For example, the electronic control unit 92 canoperate the transmission device 52 in accordance with the rotationalspeed N of the crank 26.

In addition to or instead of the first switch 74 and the second switch76, the operation device 58 can include a mode switch for switchingbetween the first mode and the second mode. In this case, the modeswitch is pushed to switch the electronic control unit 92 between thefirst mode and the second mode.

If the second switch 76 is operated in the standby mode in the secondmode, then the electronic control unit 92 can switch to the drive mode.Further, if the second switch 76 is operated in the drive mode, theelectronic control unit 92 can switch to the standby mode. In this case,the second switch 76 does not have to be continuously pushed to drivethe motor 54 that provides assistance when the rider is walking andpushing the bicycle.

What is claimed is:
 1. A bicycle controller comprising: an electroniccontrol unit that controls a transmission device, which is configured tochange a ratio of a rotational speed of a wheel of a bicycle to arotational speed of a crank of the bicycle, and a motor, which transmitstorque to an upstream side of the transmission device in a transmissionpath of manual driving force that is input to the crank, the electroniccontrol unit being configured to switch between a first mode that drivesthe motor in accordance with the manual driving force and a second modethat allows the motor to be driven to assist walking of the bicycle, andthe electronic control unit is configured to control a rotational speedof the motor in accordance with the ratio in the second mode.
 2. Thebicycle controller according to claim 1, wherein the electronic controlunit is configured to control the transmission device so that the ratiobecomes less than or equal to a predetermined first ratio while in thesecond mode.
 3. The bicycle controller according to claim 1, wherein theelectronic control unit controls the rotational speed of the motor sothat a difference between a vehicle speed before changing the ratio anda vehicle speed after changing the ratio becomes less than or equal to apredetermined value.
 4. The bicycle controller according to claim 1,wherein the electronic control unit controls the rotational speed of themotor based on a map or table stored in a memory of the electroniccontrol unit.
 5. A bicycle controller comprising: an electronic controlunit that controls a transmission device, which is configured to changea ratio of a rotational speed of a wheel of a bicycle to a rotationalspeed of a crank of the bicycle, and a motor, which transmits torque toan upstream side of the transmission device in a transmission path ofmanual driving force that is input to the crank, the electronic controlunit being configured to switch between a first mode that drives themotor in accordance with the manual driving force and a second mode thatallows the motor to be driven to assist movement of the bicycle while arider walks and pushes the bicycle, and the electronic control unit isconfigured to control the transmission device to decrease the ratio upondetection of an output torque of the motor becoming greater than orequal to a predetermined torque while in the second mode.
 6. The bicyclecontroller according to claim 5, wherein the electronic control unit isconfigured to control the rotational speed of the motor upon detectionof the transmission device changing the ratio so that a differencebetween a vehicle speed of the bicycle before the ratio is changed andthe vehicle speed of the bicycle after the ratio is changed is less thanor equal to a predetermined value.
 7. The bicycle controller accordingto claim 5, wherein the electronic control unit controls thetransmission device in predetermined cycles as long as the bicyclecontroller is supplied with power.
 8. The bicycle controller accordingto claim 5, wherein the electronic control unit detects the outputtorque of the motor from a command that operates the motor.
 9. Thebicycle controller according to claim 5, wherein the electronic controlunit detects the output torque of the motor from the current flowing tothe motor.
 10. The bicycle controller according to claim 5, wherein theelectronic control unit controls the rotational speed of the motor basedon a map or table stored in a memory of the electronic control unit. 11.A bicycle control system comprising the bicycle controller according toclaim 1, and further comprising the transmission device; and the motor;the transmission device including an internal transmission device. 12.The bicycle control system according to claim 10, further comprising aclutch that interrupts transmission of rotation of the motor to thecrank in a situation in which the bicycle moves forward.